One of the biggest challenges in delivering viscous fluid is providing a uniform, metered flow of viscous material in applications where an interruption of the flow rate or consistency of the material delivered may lead to an unacceptable product with no avenue for remediation.
A major deficiency in the prior art metering devices is fluid leaking into the interstices between the working components of the metering device. This leakage induces a deviation in operational parameters and deterioration in the viscous fluid flow.
In addition, the ability to rapidly couple a nozzle to a nozzle holder body and lock it in place is an important capability, for instance, in window manufacturing machines. When dispensing viscous adhesive fluid nozzles tend to clog, foul and become coated with the fluid readily. There is no cure for this problem other than to clean the nozzle or to replace it. Once the viscous fluid begins to set or harden on or in the nozzle cleaning becomes very difficult. Generally, it is more economical to discard the nozzle and to replace with a new one. Depending on the material dispensed nozzles may require changing many times during a work shift. A typical nozzle assembly includes a female part in the form of a nozzle holder and a male part in the form of a nozzle; the reverse situation is possible as well. The female nozzle holder is connected to metering device and the metering device is connected to a fluid source, such as a tank containing sealant used in window manufacturing operations.
Quick coupling devices for making a leak resistant connection between hydraulic or pneumatic components such as hoses, valves and fluid dispensing nozzles are known in the art. In a fluid dispensing environment, where the fluid dispensed is viscous and adhesive in nature, it tends to clog the nozzle apertures and gum up, adhere to and foul the associated machinery. For example, many standard fluid dispensing nozzles use a threaded connection for attachment to a nozzle holder or a fluid source. The threaded connections can gum up and stick if adhesive or viscous fluid finds its way into the threads. This can lead to the threaded fittings being difficult or impossible to disassemble, thereby significantly increasing the time required to connect and disconnect the nozzles from the dispensing machinery.
The utility of quick coupling nozzles is substantially reduced in applications where viscous adhesive fluids are used and where nozzles need to be changed frequently, often within a single assembly cycle. It is difficult to repeatedly and precisely position a nozzle secured by threaded connections to dispense fluid in a preferred direction as is often required in window assembly operations. Threaded connections, by their nature, rotate.
Beside threaded connections, some prior art quick disconnect nozzle assemblies require twisting and interlocking with appendages on the nozzle holder or the nozzle to hold and align the nozzle tip into a nozzle holder. Some other prior art assemblies use mechanisms with slides, ball bearings, levers and pivots to lock and position components of the nozzle assembly. These assemblies require complex manufacturing and assembly operations adding to their cost. In addition, their reliability in the field may be poor when used with viscous adhesive fluids because fluids readily infiltrate into and among the moving parts. The complex moving parts then tend to become fouled by contact with the viscous adhesive fluids.
One requirement of nozzle assemblies is a fluid tight connection between the nozzle holder or fluid dispenser and the nozzle tip. This seal must be effective but additionally must be robust enough to withstand repeated connection and disconnection operations. Prior art quick disconnect nozzle assemblies with complicated seals are not practical especially if they are inaccessible, require special seating, are coated with and gummed up by the viscous liquid used in the operations and are to be inspected and replaced often. It will be apparent to those skilled in the art that this would significantly add to the cycle time and cost of manufacturing operations.
Traditionally sealant applied to insulated glass window units have been silicone-based sealants. Silicone-based sealants require a curing time between several hours and several days before they achieve substantial strength. This has led to the need for large storage facilities in the window and door manufacturing industry in order to allow finished units to set for a sufficient period of time to achieve substantial curing of the sealants. Thus, recently there has been a move to change over to hot dispensed sealants. The hot applied sealants and adhesives reduce the need to store completed window and door units while the sealant cures thus reducing overhead and the overall cost of producing windows and doors.
However, hot applied sealant materials tend to have high levels of abrasives and corrosive components. Hot applied sealants include substantial concentrations of silicas and other abrasive materials. Thus, the use of hot applied sealants increases the level of wear on mechanical components used to dispense them.